/*

 * Copyright 2008-2009 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.nio.fs;

import java.nio.file.*;

import java.nio.file.attribute.*;

import java.nio.channels.*;

import java.io.*;

import java.net.URI;

import java.security.AccessController;

import java.util.*;

import java.lang.ref.WeakReference;

import com.sun.nio.file.ExtendedWatchEventModifier;

import sun.security.util.SecurityConstants;

import sun.misc.Unsafe;

import static sun.nio.fs.WindowsNativeDispatcher.*;

import static sun.nio.fs.WindowsConstants.*;

/**

 * Windows implementation of Path

 */

class WindowsPath extends AbstractPath {

    private static final Unsafe unsafe = Unsafe.getUnsafe();

    // The maximum path that does not require long path prefix. On Windows

    // the maximum path is 260 minus 1 (NUL) but for directories it is 260

    // minus 12 minus 1 (to allow for the creation of a 8.3 file in the

    // directory).

    private static final int MAX_PATH = 247;

    // Maximum extended-length path

    private static final int MAX_LONG_PATH = 32000;

    // FIXME - eliminate this reference to reduce space

    private final WindowsFileSystem fs;

    // path type

    private final WindowsPathType type;

    // root component (may be empty)

    private final String root;

    // normalized path

    private final String path;

    // the path to use in Win32 calls. This differs from path for relative

    // paths and has a long path prefix for all paths longer than MAX_PATH.

    private volatile WeakReference<String> pathForWin32Calls;

    // offsets into name components (computed lazily)

    private volatile Integer[] offsets;

    // computed hash code (computed lazily, no need to be volatile)

    private int hash;

    /**

     * Initializes a new instance of this class.

     */

    private WindowsPath(WindowsFileSystem fs,

                        WindowsPathType type,

                        String root,

                        String path)

    {

        this.fs = fs;

        this.type = type;

        this.root = root;

        this.path = path;

    }

    /**

     * Creates a Path by parsing the given path.

     */

    static WindowsPath parse(WindowsFileSystem fs, String path) {

        WindowsPathParser.Result result = WindowsPathParser.parse(path);

        return new WindowsPath(fs, result.type(), result.root(), result.path());

    }

    /**

     * Creates a Path from a given path that is known to be normalized.

     */

    static WindowsPath createFromNormalizedPath(WindowsFileSystem fs,

                                                String path,

                                                BasicFileAttributes attrs)

    {

        try {

            WindowsPathParser.Result result =

                WindowsPathParser.parseNormalizedPath(path);

            if (attrs == null) {

                return new WindowsPath(fs,

                                       result.type(),

                                       result.root(),

                                       result.path());

            } else {

                return new WindowsPathWithAttributes(fs,

                                                     result.type(),

                                                     result.root(),

                                                     result.path(),

                                                     attrs);

            }

        } catch (InvalidPathException x) {

            throw new AssertionError(x.getMessage());

        }

    }

    /**

     * Creates a WindowsPath from a given path that is known to be normalized.

     */

    static WindowsPath createFromNormalizedPath(WindowsFileSystem fs,

                                                String path)

    {

        return createFromNormalizedPath(fs, path, null);

    }

    /**

     * Special implementation with attached/cached attributes (used to quicken

     * file tree traveral)

     */

    private static class WindowsPathWithAttributes

        extends WindowsPath implements BasicFileAttributesHolder

    {

        final WeakReference<BasicFileAttributes> ref;

        WindowsPathWithAttributes(WindowsFileSystem fs,

                                  WindowsPathType type,

                                  String root,

                                  String path,

                                  BasicFileAttributes attrs)

        {

            super(fs, type, root, path);

            ref = new WeakReference<BasicFileAttributes>(attrs);

        }

        @Override

        public BasicFileAttributes get() {

            return ref.get();

        }

        @Override

        public void invalidate() {

            ref.clear();

        }

        // no need to override equals/hashCode.

    }

    // use this message when throwing exceptions

    String getPathForExceptionMessage() {

        return path;

    }

    // use this path for permission checks

    String getPathForPermissionCheck() {

        return path;

    }

    // use this path for Win32 calls

    // This method will prefix long paths with \\?\ or \\?\UNC as required.

    String getPathForWin32Calls() throws WindowsException {

        // short absolute paths can be used directly

        if (isAbsolute() && path.length() <= MAX_PATH)

            return path;

        // return cached values if available

        WeakReference<String> ref = pathForWin32Calls;

        String resolved = (ref != null) ? ref.get() : null;

        if (resolved != null) {

            // Win32 path already available

            return resolved;

        }

        // resolve against default directory

        resolved = getAbsolutePath();

        // Long paths need to have "." and ".." removed and be prefixed with

        // "\\?\". Note that it is okay to remove ".." even when it follows

        // a link - for example, it is okay for foo/link/../bar to be changed

        // to foo/bar. The reason is that Win32 APIs to access foo/link/../bar

        // will access foo/bar anyway (which differs to Unix systems)

        if (resolved.length() > MAX_PATH) {

            if (resolved.length() > MAX_LONG_PATH) {

                throw new WindowsException("Cannot access file with path exceeding "

                    + MAX_LONG_PATH + " characters");

            }

            resolved = addPrefixIfNeeded(GetFullPathName(resolved));

        }

        // cache the resolved path (except drive relative paths as the working

        // directory on removal media devices can change during the lifetime

        // of the VM)

        if (type != WindowsPathType.DRIVE_RELATIVE) {

            synchronized (path) {

                pathForWin32Calls = new WeakReference<String>(resolved);

            }

        }

        return resolved;

    }

    // return this path resolved against the file system's default directory

    private String getAbsolutePath() throws WindowsException {

        if (isAbsolute())

            return path;

        // Relative path ("foo" for example)

        if (type == WindowsPathType.RELATIVE) {

            String defaultDirectory = getFileSystem().defaultDirectory();

            if (defaultDirectory.endsWith("\\")) {

                return defaultDirectory + path;

            } else {

                StringBuilder sb =

                    new StringBuilder(defaultDirectory.length() + path.length() + 1);

                return sb.append(defaultDirectory).append('\\').append(path).toString();

            }

        }

        // Directory relative path ("\foo" for example)

        if (type == WindowsPathType.DIRECTORY_RELATIVE) {

            String defaultRoot = getFileSystem().defaultRoot();

            return defaultRoot + path.substring(1);

        }

        // Drive relative path ("C:foo" for example).

        if (isSameDrive(root, getFileSystem().defaultRoot())) {

            // relative to default directory

            String remaining = path.substring(root.length());

            String defaultDirectory = getFileSystem().defaultDirectory();

            String result;

            if (defaultDirectory.endsWith("\\")) {

                result = defaultDirectory + remaining;

            } else {

                result = defaultDirectory + "\\" + remaining;

            }

            return result;

        } else {

            // relative to some other drive

            String wd;

            try {

                int dt = GetDriveType(root + "\\");

                if (dt == DRIVE_UNKNOWN || dt == DRIVE_NO_ROOT_DIR)

                    throw new WindowsException("");

                wd = GetFullPathName(root + ".");

            } catch (WindowsException x) {

                throw new WindowsException("Unable to get working directory of drive '" +

                    Character.toUpperCase(root.charAt(0)) + "'");

            }

            String result = wd;

            if (wd.endsWith("\\")) {

                result += path.substring(root.length());

            } else {

                if (path.length() > root.length())

                    result += "\\" + path.substring(root.length());

            }

            return result;

        }

    }

    // returns true if same drive letter

    private static boolean isSameDrive(String root1, String root2) {

        return Character.toUpperCase(root1.charAt(0)) ==

               Character.toUpperCase(root2.charAt(0));

    }

    // Add long path prefix to path if required

    private static String addPrefixIfNeeded(String path) {

        if (path.length() > 248) {

            if (path.startsWith("\\\\")) {

                path = "\\\\?\\UNC" + path.substring(1, path.length());

            } else {

                path = "\\\\?\\" + path;

            }

        }

        return path;

    }

    @Override

    public WindowsFileSystem getFileSystem() {

        return fs;

    }

    // -- Path operations --

    @Override

    public Path getName() {

        // represents root component only

        if (root.length() == path.length())

            return null;

        int off = path.lastIndexOf('\\');

        if (off < root.length())

            off = root.length();

        else

            off++;

        return new WindowsPath(getFileSystem(), WindowsPathType.RELATIVE, "", path.substring(off));

    }

    @Override

    public WindowsPath getParent() {

        // represents root component only

        if (root.length() == path.length())

            return null;

        int off = path.lastIndexOf('\\');

        if (off < root.length())

            return getRoot();

        else

            return new WindowsPath(getFileSystem(),

                                   type,

                                   root,

                                   path.substring(0, off));

    }

    @Override

    public WindowsPath getRoot() {

        if (root.length() == 0)

            return null;

        return new WindowsPath(getFileSystem(), type, root, root);

    }

    // package-private

    boolean isUnc() {

        return type == WindowsPathType.UNC;

    }

    boolean needsSlashWhenResolving() {

        if (path.endsWith("\\"))

            return false;

        return path.length() > root.length();

    }

    @Override

    public boolean isAbsolute() {

        return type == WindowsPathType.ABSOLUTE || type == WindowsPathType.UNC;

    }

    private WindowsPath checkPath(FileRef path) {

        if (path == null)

            throw new NullPointerException();

        if (!(path instanceof WindowsPath)) {

            throw new ProviderMismatchException();

        }

        return (WindowsPath)path;

    }

    @Override

    public WindowsPath relativize(Path obj) {

        WindowsPath other = checkPath(obj);

        if (this.equals(other))

            return null;

        // can only relativize paths of the same type

        if (this.type != other.type)

            throw new IllegalArgumentException("'other' is different type of Path");

        // can only relativize paths if root component matches

        if (!this.root.equalsIgnoreCase(other.root))

            throw new IllegalArgumentException("'other' has different root");

        int bn = this.getNameCount();

        int cn = other.getNameCount();

        // skip matching names

        int n = (bn > cn) ? cn : bn;

        int i = 0;

        while (i < n) {

            if (!this.getName(i).equals(other.getName(i)))

                break;

            i++;

        }

        // append ..\ for remaining names in the base

        StringBuilder result = new StringBuilder();

        for (int j=i; j<bn; j++) {

            result.append("..\\");

        }

        // append remaining names in child

        for (int j=i; j<cn; j++) {

            result.append(other.getName(j).toString());

            result.append("\\");

        }

        // drop trailing slash in result

        result.setLength(result.length()-1);

        return createFromNormalizedPath(getFileSystem(), result.toString());

    }

    @Override

    public Path normalize() {

        final int count = getNameCount();

        if (count == 0)

            return this;

        boolean[] ignore = new boolean[count];      // true => ignore name

        int remaining = count;                      // number of names remaining

        // multiple passes to eliminate all occurences of "." and "name/.."

        int prevRemaining;

        do {

            prevRemaining = remaining;

            int prevName = -1;

            for (int i=0; i<count; i++) {

                if (ignore[i])

                    continue;

                String name = elementAsString(i);

                // not "." or ".."

                if (name.length() > 2) {

                    prevName = i;

                    continue;

                }

                // "." or something else

                if (name.length() == 1) {

                    // ignore "."

                    if (name.charAt(0) == '.') {

                        ignore[i] = true;

                        remaining--;

                    } else {

                        prevName = i;

                    }

                    continue;

                }

                // not ".."

                if (name.charAt(0) != '.' || name.charAt(1) != '.') {

                    prevName = i;

                    continue;

                }

                // ".." found

                if (prevName >= 0) {

                    // name/<ignored>/.. found so mark name and ".." to be

                    // ignored

                    ignore[prevName] = true;

                    ignore[i] = true;

                    remaining = remaining - 2;

                    prevName = -1;

                } else {

                    // Cases:

                    //    C:\<ignored>\..

                    //    \\server\\share\<ignored>\..

                    //    \<ignored>..

                    if (isAbsolute() || type == WindowsPathType.DIRECTORY_RELATIVE) {

                        boolean hasPrevious = false;

                        for (int j=0; j<i; j++) {

                            if (!ignore[j]) {

                                hasPrevious = true;

                                break;

                            }

                        }

                        if (!hasPrevious) {

                            // all proceeding names are ignored

                            ignore[i] = true;

                            remaining--;

                        }

                    }

                }

            }

        } while (prevRemaining > remaining);

        // no redundant names

        if (remaining == count)

            return this;

        // corner case - all names removed

        if (remaining == 0) {

            return getRoot();

        }

        // re-constitute the path from the remaining names.

        StringBuilder result = new StringBuilder();

        if (root != null)

            result.append(root);

        for (int i=0; i<count; i++) {

            if (!ignore[i]) {

                result.append(getName(i).toString());

                result.append("\\");

            }

        }

        // drop trailing slash in result

        result.setLength(result.length()-1);

        return createFromNormalizedPath(getFileSystem(), result.toString());

    }

    @Override

    public WindowsPath resolve(Path obj) {

        if (obj == null)

            return this;

        WindowsPath other = checkPath(obj);

        if (other.isAbsolute())

            return other;

        switch (other.type) {

            case RELATIVE: {

                String result;

                if (path.endsWith("\\") || (root.length() == path.length())) {

                    result = path + other.path;

                } else {